From a recent post on the VirtualPatients.eu website:

OpenLabyrinth cases are authored by subject-matter experts using VUE (Visual Understanding Environment), an open-source tool developed by Tufts University. This tool provides an intuitive way to develop and visualise a decision tree representing a VP case, which can then be imported straight into OpenLabyrinth.

I recently came across another open source project, msc2svg, who used a VUE map to describe the design of their software. The application they've developed is a neat utility for crunching a text document into a message sequence chart like this:
Here is the VUE map describing the design of the software:

The map file is available in their open code repository located here.

Stuart Lee from The First World War Poetry Digital Archive is using VUE to draw out relationships between poets covered in the archive. From his post at the World War One Literature google group:

What I have done, therefore, is take a preliminary stab at showing -
in a mind-map - the relationships between the poets we have
concentrated on in the project (or will be) and show how they might
have known each other, etc. By no means is this complete, but it
begins to show poets who were clearly at the centre of things
(Sassoon, Thomas, Graves, and eventually Owen) and those who were on
the periphery (Leighton, Jones, Brittain).

I came across this map today, posted in the Journey to Fletcher Blog. The actual map file isn't available but the author provided a brief description, click through to read the post. The use of color, in this case adding the blue nodes, was helpful in bringing out the central themes in what is a pretty dense map.